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JP2013197867

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DESCRIPTION JP2013197867
Abstract: In a speaker device having a dome-shaped diaphragm, when an external force is applied
to the diaphragm, the diaphragm is prevented from being damaged or deformed to such an
extent that it does not return to its original shape. SOLUTION: The speaker device 1 has a mesh
having a dome-shaped envelope surface similar to the inner surface of the diaphragm 21 in the
space between the top surface of the magnetic circuit 10 and the inner surface of the domeshaped diaphragm 21. Shaped protective structure 40. An air vent hole is provided at the center
of the magnetic circuit 10. The periphery of the protective structure 40 is fixed to the top surface
of the top plate 13 of the magnetic circuit 10 by an adhesive or the like. [Selected figure] Figure
1
Electro-acoustic transducer
[0001]
The present invention relates to an electroacoustic apparatus having a dome-shaped diaphragm
such as a dome-shaped speaker apparatus.
[0002]
The diaphragm of the dome-shaped speaker device may be broken or deformed and may not
return to its original shape when an external force is applied.
Such breakage or deformation of the diaphragm affects the acoustic characteristics of the
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speaker device. Therefore, in order to prevent external force from being applied to the
diaphragm, generally, a protective structure such as a wire mesh is installed on the outer side
(surface side) of the diaphragm. However, when the protective structure is installed outside the
diaphragm, the radiation emitted from the diaphragm is blocked by the protective structure,
which affects the acoustic characteristics of the sound emitted from the speaker apparatus to
some extent. In addition, because of the protective structure, the speaker device can not have a
free appearance design. In view of the above, Patent Document 1 discloses a technique for
preventing breakage or the like of a diaphragm by installing a protective structure inside the
diaphragm even if an external force is applied to the diaphragm. The speaker device disclosed in
Patent Document 1 has a structure in which a dome-shaped protective structure is fitted and
fixed to a supporting hole provided in a top plate of a magnetic circuit. According to the structure
disclosed in Patent Document 1, it is possible to prevent damage or the like of the diaphragm by
supporting the external force applied to the diaphragm with the protective structure provided
inside the diaphragm.
[0003]
Unexamined-Japanese-Patent No. 2010-34988
[0004]
However, in the structure of Patent Document 1, it is necessary to provide a fitting hole for
supporting the protective structure at the center of the magnetic circuit.
Therefore, the structure of Patent Document 1 can not be applied to a speaker device that
requires a central hole for air venting at the center of the magnetic circuit.
[0005]
The present invention has been made in view of the above circumstances, and can be applied to a
dome-shaped speaker device or the like having a central hole for air venting at the center of the
magnetic circuit, and protects the diaphragm from external force The purpose is to provide
technical means that can
[0006]
The present invention is accommodated in a space between a dome-shaped diaphragm, a
magnetic circuit having a central hole and generating a magnetic field acting on the diaphragm,
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and the magnetic circuit and the inner surface of the diaphragm. A mesh-shaped protective
structure having a dome-shaped envelope surface opposed to the inner surface of the diaphragm
with an air gap interposed therebetween, and an outer peripheral end is fixed to an area outside
the central hole on the top surface of the magnetic circuit. And an electro-acoustic transducer
characterized by comprising:
[0007]
In the present invention, the protective structure is fixed at its outer peripheral end to the area
outside the central hole on the top surface of the magnetic circuit.
Therefore, the present invention can be applied to an electroacoustic transducer having a central
hole for air removal in the magnetic circuit.
Then, according to the present invention, when an external force is applied to the diaphragm, the
protective structure installed inside the diaphragm supports the external force to reduce the
amount of deformation of the diaphragm, and the external force is not applied. The diaphragm
returns to the original dome shape. As a result, even if an external force is applied to the
diaphragm, it is possible to prevent the diaphragm from being damaged and being deformed so
as not to return to the original shape. In addition, since the protective structure is disposed inside
the diaphragm, it can be freely designed in appearance and does not affect the direct sound
emitted from the diaphragm.
[0008]
It is a side view showing composition of speaker device 1 which is one embodiment of this
invention. It is the perspective view which saw the protection structure 40 of the speaker
apparatus 1 in the embodiment from diagonally upper. About the speaker apparatus 1 in the
embodiment, the sound pressure frequency characteristics and the electrical impedance curve in
the case where the protective structure 40 is not provided and in the case where the protective
structure 40 is installed are illustrated with the frequency axes aligned.
[0009]
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Hereinafter, embodiments of the present invention will be described with reference to the
drawings. Embodiment FIG. 1 is a diagram showing a configuration of a speaker device 1
according to an embodiment of the present invention. In FIG. 1, in order to facilitate
understanding of the overall configuration of the speaker device 1, a side view of the protective
structure 40 is shown, and a cross-sectional view of portions other than the protective structure
40 is shown. As shown in FIG. 1, the speaker device 1 includes a vibrating body 20, a magnetic
circuit 10 for generating a magnetic force for driving the vibrating body 20, a protective
structure 40 for protecting the vibrating body 20, a vibrating body 20, and a magnetism. And a
frame 30 supporting the circuit 10 and the protective structure 40.
[0010]
The magnetic circuit 10 has a yoke 11, a magnet 12, a top plate 13 and an outer plate 14. The
yoke 11 is a metal body integrally formed of a bottom surface 11a, a side surface 11b, and an
upper surface 11c. The magnet 12 has a cylindrical shape and is fixed to the bottom of the yoke
11. The top plate 13 is a flat plate made of metal and is fixed to the top surface of the magnet 12.
The outer plate 14 is also a flat plate made of metal and is fixed on the upper surface portion 11
c of the yoke 11. Then, a central hole H having the same diameter and concentricity passes
through the yoke 11, the magnet 12 and the top plate 13. The central hole H is provided for
extracting the air inside the speaker device 1 (a portion surrounded by the diaphragm 21 and the
magnetic circuit 10) to the outside. A magnetic gap is formed between the top plate 13 and the
outer plate 14.
[0011]
The vibrating body 20 has a diaphragm 21, an edge 22, a voice coil bobbin 23, and a voice coil
24. The diaphragm 21 is a soft dome-shaped diaphragm formed by applying a phenolic resin to
cloths such as cotton, silk, and synthetic fibers. The outer peripheral end of the vibrator 20 is
supported by the frame 30 via the edge 22. The diaphragm 21 and the edge 22 may be integrally
formed. A voice coil bobbin 23 is joined to an outer peripheral end of the dome 21 of the
diaphragm 21. The voice coil 24 is wound around the voice coil bobbin 23 and inserted into a
magnetic gap provided between the top plate 13 and the outer plate 14. An audio signal is
supplied to the voice coil 24 from the outside of the speaker device 1. As a result, a driving force
is generated to vibrate the diaphragm 21 between the voice coil 24 and the magnetic gap.
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[0012]
FIG. 2 is a perspective view of the protective structure 40 in the present embodiment as viewed
obliquely from above. As shown in FIG. 2, the protective structure 40 has a plurality of
circumferential directions forming concentric circles having a plurality of radial direction
portions 43 and a dome center portion 42 directed from the dome center portion 42 to the dome
outer peripheral end 41 as a common center. It has a mesh shape consisting of the part 44 and is
integrally molded. The curvature of the dome shape of the protective structure 40 is substantially
the same as the curvature of the dome shape of the diaphragm 21 (or the curvature of the dome
shape of the protective structure 40 is slightly larger than the curvature of the dome of the
diaphragm 21). The material forming the protective structure 40 is preferably a synthetic resin
excellent in rigidity and heat resistance such as ABS (acrylonitrile-butadiene-styrene copolymer),
PS (polystyrene), or a metal (nonmagnetic material) such as aluminum. It is.
[0013]
The protective structure 40 has a dome-shaped envelope which is slightly smaller than the inner
surface of the diaphragm 21, and as shown in FIG. 1, the inner surface of the diaphragm 21 and
the top plate of the magnetic circuit 10. It is housed in the space between 13. The protective
structure 40 is opposed to the inner surface of the diaphragm 21 with the air gap interposed
therebetween. In the protective structure 40, with the dome center portion 42 positioned at the
center of the diaphragm 21, an adhesive or the like is applied to the region outside the center
hole H of the top surface of the top plate 13 with the dome outer peripheral end 41. It is fixed by.
[0014]
The distance between the protective structure 40 and the diaphragm 21 is preferably larger than
the maximum amplitude of the vibration of the diaphragm 21 so as not to affect the vibration of
the diaphragm 21. In addition, even if the dome shape of the diaphragm 21 is deformed by an
external force, the distance between the protective structure 40 and the diaphragm 21 can be
restored as much as possible to the original dome shape when the external force is released (selfrestoration) It is preferable to be small. Taking these into consideration, in the present
embodiment, the distance between the protective structure 40 and the diaphragm 21 is 3 mm.
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[0015]
In determining the opening size of the mesh-shaped opening 45 of the protective structure 40, it
is necessary to consider the size of an object that may exert an external force on the diaphragm
21. More specifically, assuming that an external force is applied to the diaphragm 21 when the
user presses the diaphragm 21 with a finger, it is necessary to make the mesh-shaped aperture
smaller than the size of the fingertip. At the same time, the mesh structure is such that the
protection structure 40 suppresses the flow of air in the dome shape of the diaphragm 21 and
installs the protection structure 40 without affecting the acoustic characteristics of the speaker
device 1. It is necessary to determine the size of the opening 45. In the present embodiment, in
consideration of the above points, the aperture ratio is approximately 60%, and the volume
occupancy ratio is approximately 6.5%. Here, the aperture ratio is the ratio of the aperture area
of the mesh-shaped aperture 45 to the area of the envelope of the protective structure 40, and
the volume occupancy ratio is between the inner surface of the diaphragm 21 and the top plate
13. The ratio of the volume of the protective structure 40 to the volume of the space of As
described above, by forming the protective structure 40 in a mesh shape and designing the
structure in detail, the rigidity against an external force can be secured without suppressing the
flow of air in the dome shape of the diaphragm 21.
[0016]
Next, measurement results of sound pressure frequency characteristics FRQ1 and electric
impedance IMP1 when the protective structure 40 is not provided in the speaker device 1
described above and sound pressure frequency characteristics FRQ2 and electric impedance
IMP2 when the protective structure 40 is installed are shown. Show. FIG. 3 is a diagram in which
the sound pressure frequency characteristics FRQ1 and FRQ2 and the electrical impedances
IMP1 and IMP2 are described with the frequency axis in common. The horizontal axis is
frequency (Hz), and the vertical axis is dB in sound pressure frequency characteristics and Ω in
electrical impedance. As is clear from FIG. 3, the sound pressure frequency characteristics and
the electrical impedance substantially match each other when the protective structure 40 is not
provided and when the protective structure 40 is provided. Therefore, the acoustic
characteristics of the speaker device 1 are not affected even if the protective structure 40 of the
present embodiment is installed inside the diaphragm 21.
[0017]
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According to the embodiment described above, when the external force is applied to the domeshaped diaphragm 21, the protective structure 40 supports the external force, and the
diaphragm 21 is not deformed inward from the protective structure 40, and the external force is
applied. When it is gone it will return to its original dome shape. For this reason, it is possible to
prevent damage to the diaphragm 21 due to external force and deformation that does not return
to the original shape.
[0018]
Further, in the present embodiment, the top plate 13 of the magnetic circuit 10 to which the
outer peripheral end 41 of the protective structure 40 is fixed supports the entire protective
structure 40. Therefore, even if the magnetic circuit 10 has a hole for evacuating the center, the
magnetic circuit 10 can support the protective structure 40. And, since the protective structure
40 has an aperture ratio and a volume occupancy that can sufficiently move the air between the
magnetic circuit 10 and the diaphragm 21, it affects the acoustic characteristics of the speaker
device 1. There is no.
[0019]
<Other Embodiments> While one embodiment of the present invention has been described
above, other embodiments can be considered in the present invention. For example:
[0020]
(1) In the above embodiment, the protective structure 40 is applied to the soft dome type
speaker device. However, the protective structure 40 of the above embodiment may be applied to
a hard dome type speaker device in which the diaphragm 21 is made of a metal material such as
aluminum, titanium or beryllium. At this time, it is preferable to determine the distance between
the diaphragm 21 and the protective structure 40 in consideration of the amplitude and the
material of the diaphragm 21.
[0021]
(2) In the above embodiment, although the aspect of applying the protective structure 40 to the
speaker device has been described, the same protective structure 40 is used to protect the
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diaphragm with respect to a microphone that converts the vibration of the diaphragm to an
electrical signal. You may apply to
[0022]
DESCRIPTION OF SYMBOLS 1 ... Speaker apparatus, 10 ... Magnetic circuit, 11 ... Yoke, 12 ...
Magnet, 13 ... Top plate, 14 ... Outer plate, 20 ... Vibrator, 21 ... Diaphragm, 22 ... Edge, 23 ...
Voice coil bobbin, 24 ... Voice Coil 30 30 frame 40 protective structure 41 dome outer peripheral
end 42 42 dome central portion 43 radial direction portion 44 circumferential portion 45
opening portion H central hole
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